The invention relates generally to steam turbines. More particularly, the invention relates to a solution for measuring steam quality in a steam turbine.
Measurement of the steam quality in a steam turbine is often desired in order to improve the turbine's performance, improve turbine control and plant control (such as tuning condenser performance, heat recovery steam generator (HRSG) adjustments and gas turbine operation). However, current methods of measuring the quality of steam in a steam turbine do not provide a means for measuring steam quality during normal operation of the turbine. For example, one current method, a tracer test, such as described in U.S. Pat. No. 4,788,848, can be performed, which basically involves the injection of a solution into the steam supply. However, the feedback from a tracer test is not immediate and typically the high costs of running such a test prohibits it from being done on a constant basis.
Alternatively, the quality of the steam can be inferred, although often inaccurately, from measurement of other data, such as total plant heat balances. In other words, an analyst can attempt to infer what quality of steam must have been present to produce other measured results. Obviously, this means of measuring steam quality has inherent limitations and does not accurately measure the quality of steam in a system.